http://www.google.com/phone/static/en_US-nexusone_tech_specs.html
Some interesting observations one hour in.
The speaker and microphone is positioned so the back of the device is how you talk on the phone. Further the camera being there one could do video conferencing and speakerphone, albiet without seeing the visual on the other end.
The device has high Ghz and low memory and flash (too low?), and SD as the storage medium. This allows a user to switch media when it fills, to shift data easily, but is the OS internal and not on the SD card or does a second card need to have an OS installed if you are a switcher?
It uses the same radio stuff as the iPhone. GSM/EDGE.
It uses micro-USB and interestingly is not in the iPhone ecosystem with a compatible dock connector.
It uses an OS with a cute name that begs the question: was the prior iteration "donut"?
The video density and resolution is higher than iPhone roughly 800x480 vs 320x480. I doubt this is meaningful on such a small screen, but I expect Google to hand their hat on it.
The clickable trackball is non-trivial. It makes practical remote desktop and "legacy interface applications".
Rocketman